Procedure Overloading

Procedure Overloading

[Justin Schaub]

Is there a way to specify which overloaded procedure is called in the
following example?

package A

type Access_Integer is access Integer;

procedure compute( Num : access Integer);
procedure compute(Num : Access_Integer);

end A;

procedure Test is
   B : Access_Integer;
begin
   compute(B);
end Test;

The GNAT compiler allows compilation of the package A, but when compiling
the procedure B it says that there is an ambiguous reference to the
overloaded compute function.

I have heard that you could simply do

compute (Access_Integer'(B));

but that didn't work either.  Any ideas?  I know it's a silly example but we
are importing the ADA GLU bindings that have a similar issue.

Justin

Re: Procedure Overloading

[christoph.grein]

Why on earth have the creators of the Ada GLU binding chosen to shoot themselves 
into the foot?

I do not see a way to resolve the overloading ambiguity (except of course 
changing the declarations :-(.

There are other ways to produce unresolvable ambiguities, e.g.

generic
  type T is private;
package G is
  procedure P (X: T);
  procedure P (X: Boolean);
end G;

with G;
package I is new G (Boolean);  -- legal, but I.P is unresovably ambiguous.

Re: Procedure Overloading

[Dmitry A. Kazakov]

On Thu, 24 Jul 2003 20:49:45 GMT, "Justin Schaub" <none> wrote:

>Is there a way to specify which overloaded procedure is called in the
>following example?
>
>package A
>
>type Access_Integer is access Integer;
>
>procedure compute( Num : access Integer);
>procedure compute(Num : Access_Integer);
>
>end A;
>
>procedure Test is
>   B : Access_Integer;
>begin
>   compute(B);
>end Test;
>
>The GNAT compiler allows compilation of the package A, but when compiling
>the procedure B it says that there is an ambiguous reference to the
>overloaded compute function.
>
>I have heard that you could simply do
>
>compute (Access_Integer'(B));
>
>but that didn't work either.  Any ideas?  I know it's a silly example but we
>are importing the ADA GLU bindings that have a similar issue.

Passing integers by pointers plus clashed types is indeed silly.

You can rename compute:

procedure Test is
   procedure compute_with_anonymous (Num : access Integer)
      renames A.compute;
   procedure compute_with_named (Num : Access_Integer)
      renames A.compute;

   B : Access_Integer;
begin
   compute_with_named (B);
end Test;

---
Regards,
Dmitry Kazakov
www.dmitry-kazakov.de